The invention relates generally to a lamp socket, and more specifically to a lamp socket for exterior lighting on a motor vehicle.
Exterior lighting systems on motor vehicles include a variety of lamps that perform functions from illuminating the roadway and the vehicle to providing indications to the drivers of other vehicles or pedestrians. The lamps used for exterior lighting on motor vehicles are typically held in lamp sockets that are, in turn, mounted in lamp housings on the vehicle. Each lamp housing is provided with one or more mounting holes in a back wall or side wall for mounting one or more lamp sockets. The lamp sockets are generally mounted in the mounting holes such that the lamp extends into the interior of the lamp housing and a wire receiving side of the lamp socket is outside the lamp housing.
Typically the mounting holes are sealed with gaskets so that the interior of the lamp housing is protected from moisture; however, the portion of the lamp socket that is outside the lamp housing may be exposed to the elements. As a result, the lamp socket is commonly sealed to prevent the entry of moisture and debris into the lamp socket which could cause premature failure of the lamp socket due to moisture and corrosion. In some sockets, sealing is provided by separate sealing boots that fit over the end of the lamp socket and have holes to accommodate electrical wiring to the lamp socket. In other designs, the wire receiving end of the lamp socket is sealed with a potting compound. One problem associated with potting the lamp socket is that steps must be taken to prevent the potting compound from entering the contact area on the lamp side of the lamp socket and interfering with the operation of the lamp. For example, U.S. Published Patent Application 20030068929 describes a socket wherein a cover plate is formed on the contact terminals to block the entry of sealing material into the contact area of the socket.
A most basic requirement of the many different lamp socket designs in use today, is the requirement that the lamp socket secure the lamp against damage, including damage from vibration that occurs during operation of the vehicle. At least some lamp sockets retain the lamp in a manner that allows for an amount of lateral lamp movement within the socket. Such lateral movement of the lamp within the socket is undesirable in that it adversely affects the interface between the lamp lead wires and the lamp socket contacts and is a common source of failure in the lighting system. In one approach to retaining a wedge base lamp, U.S. Pat. No. 5,197,187 describes a lamp socket wherein the terminal contacts include beams that retain a lamp base in the socket. U.S. Published Patent Application 20040132336 and its parent, Published Application 20030068929 describe lamp sockets that include features that, in conjunction with terminals, align, stabilize, and retain the lamp bulbs in the sockets.
A need remains for a cost effective lamp socket that provides sealing, lamp retention, and lamp stabilization that render the lamp socket suitable for use in the often harsh environment associated with motor vehicle lighting.